NITROGEN EXTRACTION AND RECOVERY
The VOLAZ plant
Advanced technology for reducing digestate volumes and utilising recovered nutrients.
VOLAZ
Nutrient recovery from digestate
VOLAZ is an innovative system for the treatment of livestock effluents and digestate from biogas and biomethane plants. Through a sequence of mechanical and technological processes, it enables the separation and utilisation of the various components of the digestate, recovering nutrients and reducing the volumes to be managed.
The treatment combines mechanical separation, nitrogen stripping and membrane filtration, transforming the digestate into various usable fractions: a solid fraction that can be used as biomass for recirculation in the digester, a fraction of concentrated ammonium sulphate rich in nitrogen that complies with RENURE criteria and can be used as fertiliser, and treated water that can be reused in the process or discharged in accordance with legal limits.
VOLAZ
How does the plant work?
The VOLAZ system treats the digestate using a sequence of integrated technologies that enable the separation and recovery of nutrients present in the effluent.
- Mechanical separation -> the digestate undergoes solid-liquid separation to remove the solid fraction and prepare the liquid for subsequent treatments.
- Nitrogen stripping -> ammoniacal nitrogen is separated from the digestate and recovered in the form of ammonium sulphate, which can be used as a fertiliser.
- Membrane concentration -> the liquid digestate is concentrated using membranes, reducing volumes and increasing nutrient concentration.
- Reverse osmosis -> this final stage produces purified water that can be reused in the process or discharged within regulatory limits.
WHY CHOOSE VOLAZ
Operational and agronomic benefits
The VOLAZ system enables the efficient management of digestate and livestock effluents, transforming them into useful resources for agriculture. The process reduces the nitrogen load in the digestate by recovering part of it in the form of ammonium sulphate, a liquid mineral fertiliser that is fully suitable for agricultural use and marketable, in compliance with RENURE criteria. At the same time, it produces purified water that can be discharged in accordance with legal limits and significantly reduces the volumes to be managed. The treatment also produces a digestate concentrate of approximately 30%, with reduced volume, rich in organic matter and low in nitrogen, which can be reused in the digester as recirculating biomass.
The results of the process demonstrate high efficiency: approximately 60% of the nitrogen is recovered as ammonium sulphate, whilst approximately 40% remains in the recirculated effluent. The system also enables a reduction in volumes to be managed of up to 85% and water recovery of approximately 55%.
Nitrogen recovery
Volume reduction
Water recovery
Concentrated digestate
VOLAZ IN ACTION
A case study
One example of its application involves a 150 Sm³/h biomethane plant fuelled mainly by livestock manure. Without advanced digestate treatment, the plant produces around 160 tonnes of digestate per day, requiring approximately 17,000 m³ of storage space and over 1,100 hectares for spreading.
With the integration of the VOLAZ system, significant results are achieved:
- storage reduced to approximately 7,900 m³
- area required for spreading reduced to approximately 190 hectares
- production of approximately 584 tonnes per year of ammonium sulphate
- production of a concentrate compliant with RENURE criteria
The system therefore enables improved digestate management and the plant’s overall profitability.
VOLAZ
FIND OUT MORE
Read the brochure “Why your property can be worth more with VOLAZ”